Remote PIPE being disconnected causing application crash

I'm hoping that someone can help me with a problem we've been having for over a month now. I'll keep it short but I can supply proc mon logs etc if required.

In a nutshell, we have around 50 users (on Windows XP machines) accessing an application (on a Windows 2003 SP1 server) over a mapped drive. This app creates a pipe to a service that runs on the application server which in turn allows the app to run a number of dll's that the app requires. For about a month now we've had issues where the users find their sessions being terminated at seemingly random intervals. After a lot of investigation (and swearing) it looks as if the key problem is that the user's pipe is being disconnected causing all the running modules to close themselves. At some point later the application tries to refresh itself and naturally bombs out becuase it can no longer access the dll's.

Additionall we have found that users access the same server, the same app via Citrix seem to be immune to these problems.

I should add that the app sends 4 calls down this pipe every 30 seconds. Every now and again the first 2 of the group of 4 will succeed and then the third will report "disconnected" leading to the shutdown.